When controlling a load that may be coupled to either an AC or DC power supply, different thresholds are typically desired to measure overcurrent conditions to enhance status reporting and self protection capability. For example, if the power supply is AC, a higher peak current can be tolerated through the load before switching the load off than if the power supply is DC. Thus, it is desirable to have two different thresholds which would be dependent on whether the load was coupled to an AC power supply or DC power supply. This creates a need to have an accurate AC/DC discernment circuit that adequately ascertains whether the load is coupled to an AC or a DC power supply.
A typical method of AC/DC discernment is to simply count the number of zero crossings on the power supply line. If a sufficient number of crossing occur, then an AC discernment is made. However, this may give false discernments especially in a noisy environment.
Hence, there exists a need for an improved load control circuit which includes automatic AC/DC discernment.